The underside of the wings are a lighter gray with white and black lines and orange and blue marginal spots near the hind-wings' tail-like extensions.

[3] These extensions twitch while at rest, and may imitate a separate head to encourage predators to go for the wings, potentially allowing the bug to survive.

Caterpillars are green with markings on the sides, covered in short yellow hairs.

[3] Like other caterpillars in the Lycaenidae family, S. melinus are attended by ants in a behavior known as myrmecophily.

[3][5] The caterpillars of the gray hairstreak butterfly consume a wide range of food plants.